Garlic mustard [Alliaria petiolata (Bieb.) Cavara and Grande; Brassicaceae] is a European biennial herb, first recorded on Long Island, New York, in the 1860s, that is expanding rapidly in northeastern and Midwestern forests in the United States and in southern Canada. Garlic mustard flourishes in moist woodlands with moderate exposure to light, but it can grow in a diversity of other habitats. It is found in natural areas, woodlots, and along edges of agricultural fields and lawns throughout North America.